1. Field of the Invention
This invention relates generally to orthopedic devices for the foot and, more particularly, to a disposable two-part non-resilient, non-stretch orthotic foot support strap system having a sole support strap member and an arch support strap member that can be adhesively applied to a foot individually or together for reducing tensile loads and stresses and providing anatomical support and stability to the musculoskeletal system and the sole, arch and heel of a foot of a user, and relief from plantar fasciitis.
2. Background Art
Many people suffer from excessive foot strain and conditions such as plantar fasciitis. Plantar fasciitis often occurs in individuals who undergo long periods of weight bearing or undergo sudden changes of weight bearing. Other factors that may lead to this condition include obesity, weight gain, jobs that require a lot of walking on hard surfaces, shoes with little or no arch support. A description of the foot structure leading to this condition is provided as background for understanding the present invention.
A dissected bottom view of a human foot 100 is shown in FIG. 1 to illustrate some of the parts of a plantar fascia 110 located in the bottom of the human foot 100. The plantar fascia 110 extends from about the location of the heel 101 to about the location of the ball 102 of the foot. The plantar fascia 110 includes medial plantar fascia 120, superficial tracts 130, a central component of the plantar fascia 140, and a lateral component of the plantar fascia 150. The separate portions of the plantar fascia 110 act as a shock absorber while walking and transfer tensile forces along the bottom of the foot 100.
A cross sectional side view of tissue and bone structure in the human foot 100 is shown in FIG. 2. The human foot 100 includes the plantar fascia 110, a plantar calcaneus 160, a talus 162, a navicular 164, a cuneiform 166, a cuboid 168, metatarsals 170, phalanges 172, a sesamoid 174, a fat pad area 176, and an outer skin surface 178. As seen from the side, the plantar calcaneus 160, the talus 162, the navicular 164, the cuneiform 166, the cuboid 168, the metatarsals 170, and the sesamoid 174 form what resembles the shape of an arch. This shape is commonly referred to as the longitudinal arch. Another arch commonly referred to as the transverse arch (metatarsal) also exists in about the same area in a perpendicular direction that runs laterally across the width of the foot.
The plantar fascia 110 provides anatomical support to the foot as it serves the vital role of maintaining the shape of the two anatomical arches of the foot, the transverse arch and the longitudinal arch. As illustrated in FIGS. 1 and 2, the plantar fascia 110 runs across the bottom of the foot 100 from the heel 101 to the ball 102 and spreads out across the width of the foot 100. As longitudinal and lateral tensile stresses are produced in the bottom of the foot 100, the plantar fascia 110 absorbs the tensile forces and maintains the shape of the two anatomical arches.
For example, while standing or while in motion, forces experienced by the foot 100 act in a direction which tends to flatten the arches. The stress line 300 in FIG. 2 shows an approximation of the line of forces transferred through foot 100 during typical motion. As shown in FIG. 2, the stress line 300 resembles the shape of an archer's bow. The plantar fascia 110 running along near the bottom surface of the foot 100 is analogous to a string in the archer's bow. Forces that tend to move the ends of the bow apart increase tension on the string. FIG. 2 also shows a sole support strap member 10 and an arch support strap member 20 of the present two-part non-resilient, non-stretch orthotic foot support strap system, illustrated somewhat schematically and with a greater thickness for visibility, attached to the sole of the foot, and will be described hereinafter.
The walking gait cycle is broken down into 3 different phases:
(1) Contact phase: The outside of the heel hits the ground. Just after the heel strikes, “pronation” occurs. Pronation is when the foot flattens out and the ankle rolls inwards. At the same time, the lower leg rotates inwards from the knee down. The pronated foot is flexible and loose, serving as a shock absorber and allowing it to adapt to the ground just stepped on. The contact phase continues until the foot is completely flat on the ground.
(2) Midstance phase: The foot is flat on the ground and in this part of the gait cycle the body weight passes over the foot as the body comes forward. This is where the foot supports the body weight. The midstance phase is the part of the gait cycle where an abnormally functioning foot, such as an over-pronated foot (fallen arches) or an over-supinated foot (high arch foot) will typically manifest its problems. This phase ends as the body weight passes forward eventually forcing the heel to rise off the ground. At this stage “supination” occurs and the opposite to pronation happens: the muscles tighten and the foot becomes a rigid lever for the leg muscles to pull against. Rigidity in the foot should occur as the foot is propelled forward towards the next step. With supination, the foot rolls outwards and the lower leg rotates externally.
(3) Propulsion phase, also known as toe-off or lift-off: This is where the foot pushes off the ground to propel the body forward. Body weight is picked up by the ball of the foot and lastly the weight is absorbed by the big toe as you push off with that foot.
It is important to understand that both pronation and supination are part of a normal walking pattern. Pronation (rolling inward) acts as a shock absorbing process and supination (rolling outward) helps to propel the foot forward
As forces on the foot attempt to flatten the arches during the foot contact phase of the gait cycle, the plantar fascia is stretched and tension on it is increased. During the propulsion phase (toe-off or lift-off) of the gait cycle the foot is used as a lever. During this phase, as the heel is raised from the ground surface, tension in the fascia often reaches its peak. A windlass mechanism formed by the fascia and its connection to the toes contributes to this increase in tension during the toe-off or lift-off (i.e. propulsion phase). The more aggressive the propulsion phase (e.g. during a sprint) the higher the peak stresses in the fascia.
The plantar fascia 110 is thick and essentially inelastic. If the tension on the plantar fascia 110 becomes excessive, the plantar fascia 110 may be damaged or injured and produce a condition called plantar fasciitis. Plantar fasciitis is a painful medical condition resulting from inflammation of the plantar fascia 110. Overstressing the plantar fascia 110 may produce tears in the plantar fascia 110 or separate the plantar fascia 110 from bone and other surrounding materials. Tearing and separation of the plantar fascia 110 produces inflammation which contributes to the intense pain experienced by plantar fasciitis sufferers, particularly after periods of rest. Frequently, the inflamed areas 305 are along the arch of the foot 100 and most often near the heel 101 of the foot as shown in FIG. 2, where the fascia has its smallest cross-sectional area.
Plantar fasciitis may be quite debilitating in that everyday activities such as walking and standing may be very painful. Typical treatments for plantar fasciitis may involve oral anti-inflammatories, ice packs, bedrest, stretching, steroid injections, night splints, wedge-shaped arch supports and compressive arch wraps. Even with these treatment options being employed many suffer in pain for periods of months. Plantar fasciitis cases extending beyond six months are not uncommon. The primary symptom is pain typically in the heel, experienced during the first few steps in the morning or after periods of rest. This pain is the result of inflammation accumulation in response to damaged tissue (i.e. micro-tears in the fascia). This inflammation which accumulates during rest, applies direct pressure to the damaged fascia and associated soft tissue, as one begins to stand, bear weight, or walk (i.e., apply load to the foot). The pain is often described as feeling like and ice pick in the heel. The pain is often described as feeling like and ice pick in the heel. The initial pain typically lessens after a few minutes of weight bearing as the fluid is pushed back into the surrounding tissue. The pain will continue to reoccur as long as damage to the fascia is allowed to continues or is prevented from healing by re-occurring stress. In extreme cases, treatment of plantar fasciitis may culminate in expensive and invasive corrective surgery. Plantar fasciitis is often experienced in only a single foot.
To gain access to the plantar fascia, surgeons may perform either an endoscopic procedure requiring small incisions or conventional direct visualization requiring the underside of the foot to be opened up. Both of which are painful, scars may result, and recovery time may be from weeks to months.
Improper treatment of plantar fasciitis may lead to other medical problems. For example, if inflammation near the heel is allowed to continue for a long period of time, calcium deposits may build-up in the damaged region. As the calcium builds-up, bony outcroppings, commonly referred to as “heel spurs” may develop in the heel. The longer the plantar fascia remains inflamed around the heel, the stronger the conditions are for the development of heel spurs. Protrusion of the heel spurs into the surrounding tissue may result in a cycle of irritation, inflammation, and pain known as heel spur syndrome. Heel spur syndrome is commonly treated with a surgical procedure requiring removal of the heel spurs from within the foot. An endoscopic procedure is typically not used for removal of heel spurs and open surgery is typically required. Recovery time from such surgery may range from weeks to months, during which time the patient has to curtail the amount of stress placed on the foot.
A common example of non-surgical treatment for plantar fasciitis is medical personnel strapping strips of adhesive tape to the bottom of an injured foot. Strips of tape are applied at various angles across the bottom of the foot. The adhesive tape is sold on rolls and is difficult to remove from the rolls and must be customized for application according to the imagination and skill of the person applying the tape. Typically, the tape cannot be effectively applied by the patient to the patient's own foot and usually requires application by another individual or a trained medical technician. The person applying the tape must cut off a section of the tape from a roll, cut the length of tape further into a therapeutic shape, and apply it to the patient. The cutting, shaping and positioning (tensioning) of the tape piece are left to the complete discretion of the person applying the tape, and it is a trial and error process. Even a trained medical technician must estimate a position, length, shape and degree of tension that will cause a subjective improvement in range of motion and pain relief in the patient. If the tapes are stretchable, this further complicates the application and decreases the likelihood of consistent and repeatable self-application. Care must also be exercised during the application of the tape to avoid blister-causing wrinkles in the tape and other problems. The tape, when subject to the cyclic tensile loads, looses effectiveness quickly as the materials elongate and the glue layers slip or creep. Multiple layers of material, glued to each other increase the opportunity for each or any of the glue layers to allow slippage as high tensile loads are applied. As the patient walks with the taped foot, the tape often works loose and stretches with time. Consequently, taping the foot is cumbersome, inefficient, and ineffective in preventing excessive stretching of the plantar fascia.
A popular commercially available high-stretch elastic adhesive tape known as KINESIO TEX™, is manufactured by Kinesio Co., Ltd. of Japan and disclosed in U.S. Pat. Nos. 5,861,348 and 7,902,420. This elastic tape is designed for maximum range of motion and provides 140% elasticity (about same as basic elasticity found in skin and muscles), allowing it to work with the body. It does not limit range of motion and ineffective in preventing excessive stretching of the plantar fascia. It is sold in rolls and also has the same disadvantages and tapping difficulties of other adhesive tapes as discussed above.
Another example of non-surgical treatment for plantar fasciitis is the use of elastic compression sock worn over the patient's foot or an elastic bandage or band worn around the mid-foot. These elastic devices exert compressive forces along the longitudinal and transverse axes of the patient's foot. While some patients may be willing to wear these elastic devices, they are inconvenient and cumbersome. In order to be installed on the foot, these elastic devices must be stretched to fit over the heel and toe or wrapped around the mid-foot. Because they are elastic, they allow the foot to move and stretch. Thus they have limited effectiveness in limiting the tensile stress on the plantar fascia, particularly during the propulsion phase of the gait cycle, as they do not limit deformation of the foot structure under load. Consequently, the plantar fascia may still be subjected to excessive tensile forces during the critical heeling process. Re-subjecting the plantar fascia to tensile forces before it has completely healed may re-aggravate damaged or injured portions of the plantar fascia and undermine the healing process. In addition, these elastic devices are meant to be worn multiple times and may require regular cleaning to avoid odors and foot infections. Also, they may not fit inside a shoe while being worn and may be considered unsightly or become contaminated while walking around without shoes.